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Date: Wed, 27 Mar 2024 22:35:58 -0300
From: Wedson Almeida Filho <wedsonaf@...il.com>
To: rust-for-linux@...r.kernel.org
Cc: Miguel Ojeda <ojeda@...nel.org>,
Alex Gaynor <alex.gaynor@...il.com>,
Boqun Feng <boqun.feng@...il.com>,
Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...sung.com>,
Alice Ryhl <aliceryhl@...gle.com>,
linux-kernel@...r.kernel.org,
Wedson Almeida Filho <walmeida@...rosoft.com>
Subject: [PATCH v3 05/10] rust: alloc: introduce allocation flags
From: Wedson Almeida Filho <walmeida@...rosoft.com>
We'll use them when allocating `Box`, `Arc`, and `UniqueArc` instances,
as well as when allocating memory for `Vec` elements. These changes will
come in subsequent patches.
Reviewed-by: Benno Lossin <benno.lossin@...ton.me>
Signed-off-by: Wedson Almeida Filho <walmeida@...rosoft.com>
---
rust/bindings/bindings_helper.h | 3 ++
rust/kernel/alloc.rs | 61 +++++++++++++++++++++++++++++++++
rust/kernel/alloc/allocator.rs | 17 ++++-----
rust/kernel/prelude.rs | 2 +-
4 files changed, 71 insertions(+), 12 deletions(-)
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 65b98831b975..ddb5644d4fd9 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -20,5 +20,8 @@
/* `bindgen` gets confused at certain things. */
const size_t RUST_CONST_HELPER_ARCH_SLAB_MINALIGN = ARCH_SLAB_MINALIGN;
+const gfp_t RUST_CONST_HELPER_GFP_ATOMIC = GFP_ATOMIC;
const gfp_t RUST_CONST_HELPER_GFP_KERNEL = GFP_KERNEL;
+const gfp_t RUST_CONST_HELPER_GFP_KERNEL_ACCOUNT = GFP_KERNEL_ACCOUNT;
+const gfp_t RUST_CONST_HELPER_GFP_NOWAIT = GFP_NOWAIT;
const gfp_t RUST_CONST_HELPER___GFP_ZERO = __GFP_ZERO;
diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index 2c99635f9fd3..fd5541991a22 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -6,3 +6,64 @@
#[cfg(not(testlib))]
mod allocator;
pub mod vec_ext;
+
+/// Flags to be used when allocating memory.
+///
+/// They can be combined with the operators `|`, `&`, and `!`.
+///
+/// Values can be used from the [`flags`] module.
+#[derive(Clone, Copy)]
+pub struct Flags(u32);
+
+impl core::ops::BitOr for Flags {
+ type Output = Self;
+ fn bitor(self, rhs: Self) -> Self::Output {
+ Self(self.0 | rhs.0)
+ }
+}
+
+impl core::ops::BitAnd for Flags {
+ type Output = Self;
+ fn bitand(self, rhs: Self) -> Self::Output {
+ Self(self.0 & rhs.0)
+ }
+}
+
+impl core::ops::Not for Flags {
+ type Output = Self;
+ fn not(self) -> Self::Output {
+ Self(!self.0)
+ }
+}
+
+/// Allocation flags.
+///
+/// These are meant to be used in functions that can allocate memory.
+pub mod flags {
+ use super::Flags;
+ use crate::bindings;
+
+ /// Zeroes out the allocated memory.
+ ///
+ /// This is normally or'd with other flags.
+ pub const __GFP_ZERO: Flags = Flags(bindings::__GFP_ZERO);
+
+ /// Users can not sleep and need the allocation to succeed.
+ ///
+ /// A lower watermark is applied to allow access to "atomic reserves". The current
+ /// implementation doesn't support NMI and few other strict non-preemptive contexts (e.g.
+ /// raw_spin_lock). The same applies to [`GFP_NOWAIT`].
+ pub const GFP_ATOMIC: Flags = Flags(bindings::GFP_ATOMIC);
+
+ /// Typical for kernel-internal allocations. The caller requires ZONE_NORMAL or a lower zone
+ /// for direct access but can direct reclaim.
+ pub const GFP_KERNEL: Flags = Flags(bindings::GFP_KERNEL);
+
+ /// The same as [`GFP_KERNEL`], except the allocation is accounted to kmemcg.
+ pub const GFP_KERNEL_ACCOUNT: Flags = Flags(bindings::GFP_KERNEL_ACCOUNT);
+
+ /// Ror kernel allocations that should not stall for direct reclaim, start physical IO or
+ /// use any filesystem callback. It is very likely to fail to allocate memory, even for very
+ /// small allocations.
+ pub const GFP_NOWAIT: Flags = Flags(bindings::GFP_NOWAIT);
+}
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index 01ad139e19bc..8cc7099d6ae1 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -2,6 +2,7 @@
//! Allocator support.
+use super::{flags::*, Flags};
use core::alloc::{GlobalAlloc, Layout};
use core::ptr;
@@ -15,7 +16,7 @@
///
/// - `ptr` can be either null or a pointer which has been allocated by this allocator.
/// - `new_layout` must have a non-zero size.
-unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 {
+unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 {
// Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
let layout = new_layout.pad_to_align();
@@ -36,14 +37,14 @@ unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gf
// function safety requirement.
// - `size` is greater than 0 since it's either a `layout.size()` (which cannot be zero
// according to the function safety requirement) or a result from `next_power_of_two()`.
- unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags) as *mut u8 }
+ unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags.0) as *mut u8 }
}
unsafe impl GlobalAlloc for KernelAllocator {
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
// SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
// requirement.
- unsafe { krealloc_aligned(ptr::null_mut(), layout, bindings::GFP_KERNEL) }
+ unsafe { krealloc_aligned(ptr::null_mut(), layout, GFP_KERNEL) }
}
unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
@@ -64,19 +65,13 @@ unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut
// requirement.
// - the size of `layout` is not zero because `new_size` is not zero by the function safety
// requirement.
- unsafe { krealloc_aligned(ptr, layout, bindings::GFP_KERNEL) }
+ unsafe { krealloc_aligned(ptr, layout, GFP_KERNEL) }
}
unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
// SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
// requirement.
- unsafe {
- krealloc_aligned(
- ptr::null_mut(),
- layout,
- bindings::GFP_KERNEL | bindings::__GFP_ZERO,
- )
- }
+ unsafe { krealloc_aligned(ptr::null_mut(), layout, GFP_KERNEL | __GFP_ZERO) }
}
}
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index c85b5972c0d3..827e4dfd77df 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -14,7 +14,7 @@
#[doc(no_inline)]
pub use core::pin::Pin;
-pub use crate::alloc::vec_ext::VecExt;
+pub use crate::alloc::{flags::*, vec_ext::VecExt};
#[doc(no_inline)]
pub use alloc::{boxed::Box, vec::Vec};
--
2.34.1
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